INTANGIBLES (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Intangible assets:
Goodwill	$ 1,035,248	$ 1,034,644
Accumulated amortization	(871,769)	(864,576)
Net intangible assets	$ 1,731,551	$ 1,754,032
Remaining weighted average amortization period in years	22 years 4 months	22 years 1 month 6 days
Intangible liabilities:
Below market lease intangibles	$ 358,940	$ 359,118
Other lease intangibles	34,924	40,141
Accumulated amortization	(163,984)	(160,985)
Purchase option intangibles	3,568	3,568
Net intangible liabilities	$ 233,448	$ 241,842
Below market leases, remaining weighted average amortization period (in years)	13 years 8 months 12 days	13 years 8 months 12 days
Other lease intangibles, remaining weighted average amortization period (in years)	42 years 9 months 18 days	40 years 9 months 18 days
Net intangible liabilities, remaining weighted average amortization period (in years)	15 years 6 months	15 years 7 months 6 days
Above market lease intangibles
Intangible assets:
Intangible assets	$ 184,705	$ 185,012
Remaining weighted average amortization period in years	6 years 10 months 24 days	7 years
In-place and other lease intangibles
Intangible assets:
Intangible assets	$ 1,347,518	$ 1,363,062
Remaining weighted average amortization period in years	24 years 3 months 18 days	24 years
Other intangibles
Intangible assets:
Intangible assets	$ 35,849	$ 35,890
Remaining weighted average amortization period in years	12 years 4 months 24 days	14 years 1 month 6 days